Professional gambler Phil Ivey is countersuing the Borgata Casino in New Jersey over nearly $10 million he won playing Baccarat in 2012 while using a high-level and controversial technique known as edge sorting.

The casino claims Ivey knowingly exploited a defect on the backs of cards from a deck he specifically requested, purple Gemaco, during four visits between April and October 2012. Playing under special conditions requested by Ivey and granted by the casino, he won $9.6 million.

After learning that Crockfords, a swanky London casino, had denied Ivey $12 million-plus in winnings over similar allegations, the Borgata filed suit in April 2014.

On Wednesday, attorneys for Ivey and co-defendant Cheng Yin Sun filed a countersuit, claiming Borgata had destroyed the decks of cards in question. Further, the countersuit claims a representative of the casino acknowledged that the casino was aware playing cards have cutting "tolerances," that Ivey never touched the cards, and that granting the special requests of high rollers was not unusual.

"Plaintiff Borgata had a duty of care at all times relevant hereto due and owing to the defendants, to maintain, sequester and preserve the precise playing cards utilized by the plaintiff in each of the casino games patronized by the defendants from April through July of 2012," the countersuit states. "Plaintiff Borgata knew that those playing cards were critically material to Ivey and Sun's defense, and knew further that destruction of those playing cards would render the defendants irrevocably prejudice in defending against plaintiff's claims and in securing judgment against the plaintiff."

Ivey, through a spokesperson, offered no comment but has maintained his innocence throughout the Borgata and Crockfords cases. Last October, a High Court in London ruled in favor of Crockfords, allowing the casino to withhold 7.7 million pounds ($12.4 million) that Ivey won playing baccarat in August 2012.

"As I said in court, it's not in my nature to cheat -- and I would never do anything to risk my reputation," Ivey said in a statement after the October ruling. "I am pleased that the judge acknowledged in court that I was a truthful witness by saying that, 'I am entirely convinced that Mr. Ivey did not consider that what he was doing was cheating.'

"I believe that what we did was a legitimate strategy -- we did nothing more than exploit Crockfords' failure to take proper steps to protect themselves against a player of my ability -- clearly today, the judge did not agree."

Ivey has been granted an appeal that will be heard in December. When granting the appeal, Lord Justice Kim Lewison stated Ivey's grounds for appeal "raise an important question [of law] and have a real prospect of success."

When edge sorting, players look for designs on the back of the cards that are asymmetrical and use them to identify the value of the cards. At the Borgata, Ivey initially posted up $1 million in exchange for a private playing area, a dealer who spoke Mandarin Chinese, an automatic shuffler and one eight-deck shoe of purple Gemaco playing cards. The requests were granted.

Sun, a known professional gambler who, according to court documents, has been banned from several casinos around the world, sat with Ivey and communicated with the dealer in Mandarin, instructing her to turn the cards in certain directions before flipping them over. This allowed them to effectively sort the deck to better expose any asymmetrical flaws of the design on the back of the cards, without touching them.